My experience--tuned membrane traps.
Background: My room is already heavily treated for bass resonances, but there are still resonances around the 40Hz range that have been difficult to control. I have been interested in tuned membrane traps because they are designed to tame a very specific and narrow frequency band. Having done a lot of business with GIK, I researched their Scopus product, which is a tuned membrane trap coming in three standard models, the T-40, T-70, and T-100, targeted for 40Hz, 70Hz, and 100Hz, respectively. Each is a 2'x2' panel, varying in thickness from 4.5" for the T-70 and T-100, and 10.25" for the T-40. GIK will build special-order Scopus traps that target any frequency at no additional cost.
I have limited space left in my listening room, and felt that I could accommodate no more then four panels. I ordered them, and they arrived earlier this week:
The traps are a plywood box, sealed in back, and covered with the typical GIK fabric. The traps are heavy, 30lbs each. Build quality is good.
I have received differing recommendations regarding where to place the traps to maximize effectiveness. Some have recommended placing the traps according to which room dimension is creating the standing wave. Others recommended generating a standing wave at the target frequency using REW's signal generator, and then measuring the SPL at various potential mounting locations. looking for the highest SPL. I decided on the latter method. As expected, locations at boundaries between walls, wall and floor, and wall and ceiling produced the highest SPL readings. The highest reading, by almost 10dB, was along the front wall on the floor. That is where I placed the traps:
I took careful measurements before and after installing the traps, being careful to place the mic in the same spot. results:
So, how effective are the membrane traps? A slight frequency response at 48Hz is several dB's better. It's hard to say, but the Waterfalls may show a slight improvement below 40Hz. The Spectrogram, our new favorite measurement, shows a decrease in ringing at 40Hz, from 620ms to 490ms, which isn't bad.
So, given the expense of the four Scopus traps, did I get my money's worth? Not sure. Feedback would be appreciated.
Edited by AustinJerry - 11/9/13 at 9:51am